How much SSD capacity is lost in formatting?

Discussion in 'hardware' started by appster, Jan 8, 2017.

  1. appster

    appster Registered Member

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    Say I buy an SSD that is spec'd at 500GB. What should I expect the 'actual (available) capacity' of the drive to be after Windows formats it?
     
    Last edited: Jan 8, 2017
  2. Krusty

    Krusty Registered Member

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    250GB SSDs have 232GB available. Not much help with the 500GB though.
     
  3. appster

    appster Registered Member

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    So in your situation formatting "consumed" about 7% of the stated capacity. I wonder if that "loss percentage" occurs for any stated capacity?
     
    Last edited: Jan 8, 2017
  4. guest

    guest Guest

    You'll have 465 GB available after formating it.
     
    Last edited by a moderator: Jan 10, 2017
  5. appster

    appster Registered Member

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    That's good info - thanks mood!
     
  6. Minimalist

    Minimalist Registered Member

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    If "problem" is caused because decimal prefix is used instead of binary, why don't they use binary insted and end this confusion? https://en.wikipedia.org/wiki/Kibibyte
     
  7. Brian K

    Brian K Imaging Specialist

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    appster,

    It's nothing to do with formatting. A 500 GB drive is the same as a 465.7 GiB drive. Microsoft reports drive size in GiB. You don't lose any capacity.
     
  8. Bill_Bright

    Bill_Bright Registered Member

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    Yes you do. You are correct that it's not about the actual formatting (though some space is set aside for the file and partition tables). But note this question is about SSDs, not hard drives.

    So first, it is NOT that Microsoft does this or that. It that memory is measured in base binary numbering, not base decimal. That is, Microsoft does it correctly by calling 1 kilobyte 1024 bytes because 2 to 10th power (2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2) equals 1024. Therefore, 1KB = 1024 Bytes.

    Drive (and RAM) makers on the other hand, "market" their drives based on what non-technical marketing weenies claim, that is that, 1KB = 1000 Bytes. In this way, they can market the drives as being bigger.

    So mood is exactly correct in that respect.

    Second, SSDs need "reserved" space to prevent them from being filled up completely. This space is then used for TRIM and wear leveling to greatly extend the life of SSDs. This process is called "over provisioning" and typically is 6.7% of the total capacity, normally rounded up to 7% of the drive's capacity.

    So you do indeed lose some capacity with SSDs - about 7%.

    For example, I have a 256GB 850 Pro as my C drive and it shows up as 237GB. I also have a 250GB 850 EVO as my D drive, and is shows up as 232GB.

    256 - 7% = 238.08 (which is pretty close to 237)
    250 - 7% = 232.5 (which is real close 232)

    With a 500GB SSD, you will end up with about 465GB of usable space as 500 - 7% = 465. That's 500 x .93 = 465.

    Understanding SSD over-provisioning.
     
  9. Robin A.

    Robin A. Registered Member

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    The question is if this space used for over-provisioning shows up in the capacity, or if it´s internal space. I suppose the latter is true, so the reported capacity reflects the GB/GiB factor, and the real, effective capacity is less than the reported one, due to the over-provisioning thing.
     
  10. Bill_Bright

    Bill_Bright Registered Member

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    No, it does not show up. I thought I illustrated it pretty clear. My 256GB drive shows up as only 237. My 256GB drive as 232. Those values equal 7% set aside for over provisioning.

    Don't worry about 1000 vs 1024 issue. That's just marketing. The real issue is the 7% that is set aside.
     
  11. EvjlsRain

    EvjlsRain Registered Member

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    [the announced capacity] * 0.931 = ...

    32Gb -> ~29.7Gb
    500Gb -> ~465.5Gb
     
  12. Robin A.

    Robin A. Registered Member

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    Then what happens in hard disks? They show the same 7% reduction, and there is no any over-provisioning.
     
  13. Cruise

    Cruise Registered Member

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    HDD, SSD, or any other computer storage device - it's DECEPTION by those who market computer storage devices. They over-report the amount of usable storage!
     
  14. guest

    guest Guest

    Marketing (as mentioned above)
    4000 GB sounds better than 3725
     
  15. Minimalist

    Minimalist Registered Member

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    Shouldn't they be using binary prefix if they use binary numebring?
    IMO correctly would be:
    2^10 = 1024 = kibibyte (KiB)
    10^3 = 1000 = kilobyte (KB)
    It's definitely more logical then
    2^10 = 1024 = kilobyte o_O
    Binary numbering and decimal prefix just doesn't make sense to me.
     
  16. Minimalist

    Minimalist Registered Member

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    Also interesting article on IEC site:
    http://www.iec.ch/si/binary.htm
     
  17. Minimalist

    Minimalist Registered Member

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    If that means 4.000.000.000.000 bytes then all is well :). But Windows will probably tell you it's 3725 GB instead of 3725 GiB.
     
  18. Bill_Bright

    Bill_Bright Registered Member

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    Deception is a harsh word. It's marketing though many might be justified to say marketing and deception are the same things. But the fact is, it is not really deception. Remember, this 1024 value came about LONG BEFORE memory products (RAM, drives, etc.) became consumer products - that is, way back in the main frame days, back when computers where only used by governments, research facilities and big corporations - as far back as World War II even for missile trajectory calculations.

    It is more just one of those confusing things. We don't say a kilometer is 1024 meters. Or a kilogram is 1024 grams because those measuring units are done in base10, not base2. But everything in computers is based on the lonely 0 or 1, high or low, on or off - that is, binary. Why is the first drive or first RAM slot called drive 0 or slot 0? Its confusing but not done to deceive.
    That would be nice, but who's going to dictate then inforce that? No one.
     
  19. Cruise

    Cruise Registered Member

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    Perhaps, but it's definitely misleading. Interestingly enough, OS X perpetuates this misleading practice by reporting the drive's storage capacity using the overstated decimal storage value!
     
    Last edited: Jan 9, 2017
  20. Bill_Bright

    Bill_Bright Registered Member

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    If it is 7%, it is just by coincidence. Formatting a hard drive does consume some space. Like a file cabinet able to hole 1000 sheets of paper, some space is taken up by the folders, dividers, and an index.
    "Misleading" suggests intentional deception. It is not. There is no industry standard for which method will be used to report disk space.
     
  21. Bill_Bright

    Bill_Bright Registered Member

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    And FTR, this is nothing new. This discussion has been going on since the days home computers came with floppy disks only (back to my Commodore 64 days and before) in the late 1970s that I am aware of - probably before. Its what happens (in any industry) when two companies or groups of companies develop separately, a new technology (or parts of the same technologies) via different paths. Unless from day one, they all agree on common terms and conditions, consumers end up having to deal with confusion.
     
  22. Cruise

    Cruise Registered Member

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    Sorry Bill, but (with all due respect) I'm not buying that.

    Happy new year!
     
  23. Bill_Bright

    Bill_Bright Registered Member

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    You are not buying what?

    What would be the point of Apple or Microsoft intentionally misleading their users here? Neither is a hard drive, SSD or RAM maker.

    I think you are just looking for some one to blame for a problem that is no one's fault. Why do we in the US say gas, hood and trunk when the British say petrol, bonnet and boot? It is because there were no standards for the terms when companies in both countries developed those industries.
     
  24. Krusty

    Krusty Registered Member

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    Bill, my PVR, or as you yanks call them, a DVR, which doesn't use any common OS that I'm aware of has a 500 GB HDD with 465.7 GB available. Coincidence? I think not.
     
  25. Minimalist

    Minimalist Registered Member

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    If it doesn't have common OS then "what" tells you it's only 465.7 GB available?
     
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